Grain elevators, feed mills and flour mills continue to experience explosions with associated disastrous results, yet there is lack of understanding of the role of various aspects which bear on this hazard. It is the objective of this proposed research to determine the importance of the many factors that enter so that the appropriate safety steps can be taken. To accomplish this, controlled combustion tests would be conducted in a Flame Acceleration Tube along with an accompanying analytical treatment. One part of the facility would consist of a long, relatively large pipe with 90 degree takeoffs and with various internal treatments. This would be an approximation to a full-scale building. In this facility the variables would include type of dust, size of particles, concentration, dispersion of the dust, initial pressure temperature, and humidity, ignition sources, and dust moisture content. Attention would also be given to extinguishants and venting. In these experiments, the pressure-time results, the flame velocity, and the gas velocity would be determined at a number of locations. In addition, photography of the raising of the dust in front of the flame would be obtained. A second part of the facility would consist of a Constant Volume Explosion Chamber, an improved version of the Hartmann bomb. The conditions would be carefully controlled and experiments conducted to determine minimum ignition energy, flame propagation rates, concentration limits, and pressure rise characteristics. The experimental results from both phases of the project would be combined and interpreted. The experimentally collected data will support the development of an analytical model of the dust flame. The resultant information would then be considered as to the impact on the safety aspects of grain elevators and mills. The dusts tested need not be restricted to those of agricultural origin but could also include pharmaceuticals, wood products, or even coal.